The following meanings for the abbreviations used in this specification apply:
3GPP 3rd generation partnership project
AF application function
BBERF bearer binding and event reporting function
CAN connectivity access network
DRA diameter routing agent
EPC evolved packet core
E-UTRAN evolved universal terrestrial radio access network
GCSEL group communication system enablers for LTE
GW gateway
ID identity, identifier
IMSI international mobile subscriber identity
IP internet protocol
LTE long term evolution
OCS online charging system
OFCS offline charging system
NPSTC national public safety telecommunications council
PCC policy and charging control
PCEF policy and charging enforcement function
PCRF policy and charging rules function
PDN packet data network
P-GW packet data network gateway
QoS quality of service
SPR subscription profile repository
TDF traffic detection function
TR technical report
UDR user data repository
UE user equipment
Some embodiments of the present invention relate to usage monitoring. Usage monitoring can be applied to an accumulated usage of network resources on a per IP-CAN session and user basis. This capability is required for enforcing dynamic policy decisions based on the total network usage in real-time.
A PCRF that uses usage monitoring for making dynamic policy decisions sets and sends applicable thresholds to a PCEF or TDF for monitoring. The usage monitoring thresholds may be based e.g. on volume or actively used time. The PCEF or TDF notifies the PCRF when a threshold is reached and reports the accumulated usage since the last report for usage monitoring.
The usage monitoring capability can be applied to an individual service data flow, a group of services data flows, or to all traffic of an IP-CAN session in the PCEF. Usage monitoring, if activated, is performed both for service data flows associated with predefined PCC rules and dynamic PCC rules, including rules with deferred activation and/or deactivation times while those rules are active.
A usage monitoring group, when only a single user/UE is connected, is a set of service data flow(s)/application(s) of a user/UE that share a common traffic usage allowance and need to be monitored together for usage monitoring control purposes. Within a wider concept addressed in this application, a usage monitoring group comprises service data flows/applications of several users/UEs that share a common traffic usage allowance and need to be monitored together for usage monitoring control purposes.
The present application is not only directed to usage monitoring groups, but also other kinds of policy controlled groups. For example, 3GPP SA21 has a Rel-12 work item on Group Communication System Enablers for LTE (GCSEL), refer to the draft 3GPP TS 22.468. The scope of the WI reads as follows:
The present document collects the requirements as relevant to improve the EPC and E-UTRAN for system enablers to the 3GPP system to support group communication over LTE for Public Safety. The application layer making use of the group communication service enablers specified below is out of scope of this work. The US requirements as specified in NPSTC (Mission Critical Voice Requirements) are taken as starting point. Other regional requirements may also be reflected in the work. The requirements shall be worded in a way to easily accommodate future requirements from other regions or stakeholders.
Among other things, the following requirements should be fulfilled (e.g., 3GPP document S1-122127):                The group coordinator can add and delete group members. UEs shall be notified of being added to or deleted from a group.        The group-coordinator may link together two or more groups temporarily.        Linking shall immediately take effect. Alternatively the group coordinator shall be able to request linking to take place on idle groups, i.e. on groups where no UE is transmitting. Groups that are active, i.e. in which the floor is taken, while the linkage was initiated shall be linked to the already linked groups once they become idle.        UEs being members of the linked groups shall receive a notification of which groups have been linked together.        
3GPP SA2 has also a Rel-12 study on Usage Monitoring Control PCC Enhancements, refer to the prior art draft TR 23.858. One of the key issues of this study is Usage Monitoring for Subscriber Group.
Handling of subscriber groups may involve problems, as will be described in the following.
Mobile networks typically apply the “always-on” principle, i.e. when a UE is switched on, it attaches a mobile network and establishes a default context/bearer with the network. And if policy and charging control (PCC) is deployed in the network, the network allocates a policy and charging control function (PCRF) for the UE and its network context. This relationship is maintained as long as the UE is connected to the network.
A major problem with this is that if the user/UE is included/added in a policy and/or charging controlled group while already being attached to the network, the UE and the rest of the group members may be served by different PCRFs, selected upon IP-CAN session establishment. Handling of common/group related policy and/or charging control activities, e.g. monitoring of the usage of common quota, would be impossible or very complicated with several PCRFs involved in the process.
The problem is acute within the Group Communication System Enablers for LTE (GCSEL) work item even without an “always-on” principle, because it quite obviously does not make sense that possible to-be-joined-into-a-public-safety-group subscribers were not online/connected and because the joined-in subscribers shall be notified of being added to the group.